In recent years, in consideration of strengthening of legal regulation and environmental protection or safety, a printing ink not containing the toluene that has been suitably used as a conventional solvent of printing ink, and further minimizing a ketone solvent and an ester solvent as possible has been demanded increasingly. As such a solvent, an alcohol solvent has received a lot of attention. In particular, it is desired that the bio-ethanol having lower environmental impact is effectively used. In Patent Document 1, there is a disclosure of the dispersion of titanium white, in which as a solvent, ethanol is used as the main component.
However, in the case of a printing ink in which alcohol is used as the main solvent, a binder resin is required to be alcohol solubilized, that is, hydrophilized. Titanium white having hydrophilic particle surface and hydrophilized binder resin have compatibility with each other. However, in an organic pigment having hydrophobic surface such as a copper phthalocyanine indigo blue pigment, the compatibility with a hydrophilized binder resin is deteriorated, as a result, a problem that the dispersion stability of pigment cannot be ensured was caused.